A triac dimmer installed in series with a power supply and an incandescent lamp in a light circuit, controls how much power is delivered to the lamp and in turn controls how bright the lamp shines. The triac dimmer cuts off a portion of supplied power and allows only a portion of the supplied power to pass to the lamp, depending on the setting of the triac dimmer. Alternating current being delivered to the light circuit from the power supply rapidly fluctuates from positive voltage to negative voltage in the form of a sine wave. The light circuit switches the lamp off and on every time the sine wave switches directions and crosses zero. The triac dimmer is able to control the amount of power being delivered to the lamp by only turning the light circuit back on after the voltage reaches a certain level after crossing zero. The level is defined by the setting of the triac dimmer. In other words, the triac dimmer chops up the supplied voltage. Thus, a user is able to dim an incandescent lamp to a desired brightness by adjusting the triac dimmer.
Compact fluorescent lamps (CFLs) are increasingly popular replacements for incandescent lamps. A CFL uses less power and lasts longer then an incandescent lamp. Dimmable CFLs, such as the early generation 16W R30 Dimmable CFL lamp from TCP has been developed to function similarly to dimmable incandescent lamps. However, known dimmable CFLs do not have the same dimming range as an incandescent lamp. Specifically, known dimmable CFLs do not dim satisfactorily to low levels, such as 20% of full power or less. Additionally, known dimmable CFLs are unable to start at low settings. Instead, a user must move a dimmer to a higher level before restarting the dimmable CFL. Once the CFL is powered up again, the user may then adjust the dimmer back down to a lower setting. Further, known dimmable CFLs have a long light output run up time. It can take 60 second or more for a known dimmable CLF to reach full brightness. Also, known dimmable CFLs have an abrupt dimming curve, in contrast to a smooth and stable dimming curve of an incandescent lamp.